Journal of
Science and Technology-The University of Danang, JST-UD, is an
independent peer-reviewed journal, applying international standards, inheriting
the achievements of 40 years of scientific and technological information
activities of Da Nang University and member institutions.
JST-UD operates under License No. 510/GP-BVHTT, dated November 25, 2002
by the Ministry of Culture and Information and international standard code ISSN
1859-1531 (according to Official Letter No. 44/TTKHCN-ISSN, February 6, 2007 of
the National Center for Scientific and Technological Information under the
Ministry of Science and Technology). It is a scientific journal with a high
number of access and reference.
JST-UD publishes quality scientific works in Vietnamese, English or
French (License No. 210/CBC, 5 March 2008 of the Press Department, Ministry of
Information and Communication) and Published yearly 15 numbers, including 3 in
English (License No. 07 / GP-BTTTT, January 7, 2016 by the Ministry of
Information and Communication).
The Journal
"Science and Technology" of the University of Danang is for purposes:
- Publishing new and multi-disciplinary
scientific and technological research works;
- Reviewing information on advances in
science and technology for the teaching, research and study of lecturers and
students;
- Propagating the guidelines and policies
of the Party and the State in the fields of education, training as well as in
scientific and technological researches.
JST-UD is pleased to receive many-sided cooperations of scientists,
educators, researchers in and outside the University of Danang as well as
national and international researchers to improve the prestige and the quality
of the Journal.
CURRENT ISSUE | Vol. 18, No. 5.1, 2020
Author: ,
Code: JST-UD2020-060 | Page: 1-5 of Vol. 18, No. 5.1, 2020 |
AbstractThis paper presents an integral method in order to model the structure with thin conductive and magnetic regions and electric circuit system. The electric sytem is descried by the equation circuit, while shell element formulation is used for thin regions. The interaction between thin regions and electric circuit system is presented. The proposed method facilitates modelling conductors with complex shapes and various skin effects across thickness of the shell taken into account. A real power station is modeled by using the integral equation system. In addition, the results compared with the finite element method also prove the accuracy and great potential of this integral method.
Author:
Code: JST-UD2020-098 | Page: 6-10 of Vol. 18, No. 5.1, 2020 |
AbstractCost-benefit analysis (CBA) is one among tools widely used for policy and project analysis around the world. In order to enhance quality of decision making by government and its agancies, the environmental impacts of projects/polices have been incorporated in CBA process. The method itself seems to be simple, but there are a number of technical problems existing in applying CBA to environment management issues. This paper firstly reviews the welfare economics foundation of CBA to show the well-established theoretical base of this analysis method; and then briefly describes the common stages in CBA process. From such methodological reviewing, potential problems in applying CBA to environmental issue within economic projects and policies are pointed out and critically argued. Those are aimed to assist policy makers obtaining a better use of CBA tool in their decision making process in order to select the best projects/policies in terms of efficiency, efectiveness and equality to society.
Author: Lương Huỳnh Vủ Thanh, Trần Chương Yến Nhi, Huỳnh Thị Kim Huệ, Ngô Trương Ngọc Mai, , Phuong Lan Nguyen Tran*
Code: JST-UD2019-156 | Page: 11-15 of Vol. 18, No. 5.1, 2020 |
AbstractThis research aims to investigate the feasibility of combining 3 by-products, namely cockle, rice husk ash (RHA), and coir pith in permeable concrete.The experiments ofvariation of water/cement ratio at 0.35, 0.4, 0.45, 0.5 and replacement of cockle by RHA at 0%, 3%, 5%, 10%, 15% (by weight) are conducted to evaluate the compressive strength and water absorption of permeable concrete.By applying into reality, the pavement tiles are produced based on the optimum mixture formula. In this study, the compressive strength, water absorption, and abrasion test are conducted following the national standards for permeable concrete. The results show that compressive strength, water absorption, and abrasion at the 28-day age of the bricks are 280.88 daN/cm2, 6.67%, and0.218 g/cm2, respectively. This result confirms that the combination of cockle, rice husk ash (RHA), and coir pith in permeable concrete is feasible to produce interlocking concrete bricks following the national standards.
Author:
Code: JST-UD2020-034 | Page: 16-19 of Vol. 18, No. 5.1, 2020 |
AbstractPoly(vinyl alcohol) (PVA)/chitosan (CTS) biodegradable films have been fabricated by solution casting. Glutaraldehyde (GA) is used as a cross-linking agent to enhance the water resistance and mechanical strength of films. The results of the study show that the water swelling of films containing CTS decreases nearly 50%. In addition, the swelling of PVA/CTS films with CTS content ranging from 5% to 15% is approximately the same. The tensile strength of PVA/CTS films increases with the content of CTS; however, when the CTS content in the films reaches 15%, the tensile strength decreases. Antibacterial test using Bacillus Subtilis bacteria shows that the films containing CTS have antibacterial properties. After 50 days being buried in soil, the films show the biocompatibility, but signs of biodegradation during this burial period are not visible.
Author: , , , Trương Đình Minh Đức
Code: JST-UD2020-057 | Page: 20-25 of Vol. 18, No. 5.1, 2020 |
AbstractMaximum power point tracking (MPPT) techniques are widely used in most photovoltaic (PV) systems to optimize the PV system’s output power which depends on ambient conditions, i.e. solar radiance and PV arrays’ temperature. In general, MPPT techniques can be classified into two categories: conventional algorithms, such as Perturbation and Observation (P&O) algorithm and Incremental Conductance (INC) algorithm, and artificial intelligence algorithms, such as Fuzzy Logic (FL). In this paper, a survey of these algorithms is conducted in order to analyze, compare and evaluate their performances when they are integrated in a PV power system under dynamic changed conditions. The simulation results, obtained by MATLAB/SIMULINK, have pointed out that the dynamic performances of MPPT based FL control are much better than those of P&O and INC algorithms.
Author:
Code: JST-UD2020-082 | Page: 26-28 of Vol. 18, No. 5.1, 2020 |
AbstractInternal erosion is one of the main causes of instabilities within hydraulic earth structures. Four types of internal erosion can be distinguished: concentrated leak erosion, backward erosion, contact erosion and suffusion. This paper relates the suffusion which causes the change of grain size distribution, porosity and hydraulic conductivity in the earth dam, dike. According to [1] an expression of the erosion resistance index as a function of fourteen physical parameters: dry unit weight, blue methylene value, internal friction angle, initial hydraulic conductivity, minimum value of ratio H/F, percentage of finer fraction (based on Kenney and Lau’s criteria), gap ratio includes Gr, d5, d15, d20, d50, d60, d90 (diameters of the 5%, 15%, 20%, 50%, 60%, 90% mass passing, respectively) and P (percentage finer than 0.063mm). Besides, the two relation equations for the gap-graded soils and widely-graded soils are also shown. Based on the classification of suffusion through the erosion resistance index (Iα), the paper assesses the suffusion susceptibility of earth dam of Dien Truong reservoir-Quang Ngai. The results show that the earth dam classification is “Moderately Erodible” at the initial section.
Author: Anh, Đức Phạm*, , , Tôn Nữ Huyền Trang
Code: JST-UD2020-039 | Page: 29-32 of Vol. 18, No. 5.1, 2020 |
AbstractFuruta pendulum, also known as “the inverted rotary pendulum” is a 2DOF model for control platform with initial movement created by a rotary motor. This pendulum model is a good platform not only to implement theoretical control methods but also to evaluate the vibration characteristics of a 2DOF mechatronics system. Despite the regularity of this control platform, few papers have used the dynamics model and vibration characteristics of Furuta pendulum in detail. Thus, this paper presents a mathematical model for the movement of Furuta pendulum based on Euler-Lagrange equations. Furthermore, a simulation model for system control and movement features of this pendulum is established in Matlab environment. Based on the identified parameters of the system, all vibration characteristics of Furuta pendulum are clearly illustrated.
Author:
Code: JST-UD2019-218 | Page: 33-37 of Vol. 18, No. 5.1, 2020 |
AbstractMemristor crossbar array is promising for realizing artificial neural networks. Wire resistance in crossbar array is one of the factors that degrade the performance of memristor crossbar circuit. In this article, we analyze the effect of wire resistance on the output voltage of crossbar array and add the differential amplifier circuits to the crossbar array to mitigate the voltage variation caused by wire resistance. In memristor crossbar array, the voltage variation caused by wire resistance is proportional to the length of metal line. In addition, two adjacent columns have the same voltage variation. Under these observations, a differential amplifier circuit is used to compensate the voltage variation of two adjacent columns. When wire resistance is 2.5Ω, the recognition rate is as low as 76%. However, if the differential amplifier circuits are added to the crossbar circuits, the recognition of the crossbar circuit is as high as 97%. Adding the differential amplifier circuit to memristor crossbar circuit can mitigate the impact of wire resistance in memristor crossbar circuit significantly
Author:
Code: JST-UD2020-010 | Page: 38-41 of Vol. 18, No. 5.1, 2020 |
AbstractIn this paper, we present a denoising model based on the variation approach. To better denoise and preserve edges, we propose an adaptive total variation term based on a weighted function, values of which are adapted to the features of pixels. The mean curvature is used to describe the features of images and adjust values of the weighted function, i.e. strength of smoothing of the model. The Split Bregman is applied to solve the minimization problem. The numerical results demonstrate that the proposed model yields better denoising performance compared with the classical model in both terms of quantitative and qualitative criteria
Author: , ,
Code: JST-UD2020-050 | Page: 42-45 of Vol. 18, No. 5.1, 2020 |
AbstractMedical sector is one of the complex domains that needs continuous improvement and enhancement of its quality in current society. This paper points out the problem in medical field related to collaboration and data sharing, with focus on the patient treatment process requiring prosthesis implantation. This treatment process includes many stakeholders in both medical domain (nurse, radiologist, medical doctor, surgeon…) and engineering domain (design engineer, producer…). The research analyzes and describes a solution based on PLM(Product Lifecycle Management) approach to solve the problems in the treatment process. Then all solutions will be implemented into Audros PLM software to demonstrate the functions of system.
Author: , Nguyễn Đỗ Dũng
Code: JST-UD2020-031 | Page: 46-51 of Vol. 18, No. 5.1, 2020 |
AbstractMillimeter Wave channels are the solution chosen for 5G systems. One of the notable challenges considered in the physical layer (PHY) for implementing these transmission systems is the trade-off between energy source and spectrum through the use of advanced MIMO techniques. In this paper, we study MIMO techniques in combination with space time shift keying STSK and constant-frequency division multiplexing CE-OFDM over-frequency-selective mm Wave channels. The space time equalizer STE is recommended for use in receiver but warrants the system complexity as low as possible. The simulation results show that the CE-OFDM STSK MIMO system with STE equalizer considering the nonlinear high frequency amplifier achieves superior performance and spectral efficiency for millimeter Wave communications.
Author:
Code: JST-UD2020-011 | Page: 52-55 of Vol. 18, No. 5.1, 2020 |
AbstractNowadays, unburnt bricks have been used across the country to replace burnt clay bricks because compared to burnt clay bricks, unburnt bricks have many advantages such as less use of agricultural soil, environmental protection, high automation capability … Besides, plastic waste is currently an alarming problem to the environment not only in Vietnam but also all over the world. Therefore, to solve environmental problems along with improving some disadvantages of unburnt bricks such as large volume mass,… this study is aimed at using waste plastic to replace a part of stone dust in the production of unburnt bricks. The results show that the maximum PET plastic waste ratio must be 12,5% in order to ensure the standard requirements of execution and compressive strength. This study indicates the possibility of reusing PET plastic waste to minimize environmental pollution.
Author: , Phan Văn Sơn, Nguyễn Thành Duy
Code: JST-UD2020-022 | Page: 56-59 of Vol. 18, No. 5.1, 2020 |
AbstractIn this paper, the authors propose a concept of a high performance of Vietnamese sesame seed candy packaging model. Sesame seed candy is a speciality of the Central Vietnam, especially of Hue, the ancient capital of Vietnam. Sesame seed candy is mainly crafted in some traditional villages in Hue. Because of handicraft, the performance of packaging process is low, and the appearance of packages is not so attractive. Two important physical characteristics of sesame seed candy are stickiness and softness. The material used for the package is mainly nylon. Those combinations trouble the automatic packaging process. The proposed model has the following advantages compared to tackle those obstacles: precise and homogeneous package, high performance, and easy maintenance. The model can be studied to make a closed, automatic sesame seed candy manufacturing system in the future.
Author: , Lê Văn Dương
Code: JST-UD2020-014 | Page: 60-63 of Vol. 18, No. 5.1, 2020 |
AbstractFor electronic devices, solder joint is a weakness that easily leads to failure during working. Therefore, the diagnosis of failure of the joint, especially determining the path of a crack, is very important. The development of modern analytical measurement techniques is very necessary and has received much attention from scientists around the world.One of the newly methods to solve the problem is Digital Image Correlation (DIC) and FEM as well.Thus, in this study, the digital image correlation and FEM methods will be used to determine the crack propagation of InnoLot lead-free material. The results of the study are important in predicting the failure of materials in order to prevent failure.
Author:
Code: JST-UD2019-137 | Page: 64-69 of Vol. 18, No. 5.1, 2020 |
AbstractThis study aims at finding effective microbial strains for wastewater aerobic treatment of ethanol plants.. Through screenings, three bacterial strains with high amylase, cellulase and protease activities have been isolated and selected. The experimental results have identified the appropriate time for culturing of selected bacterial strains to create activated sludge, with propagation time in 250 mL glass triangle flasks in 36 hours, propagation in larger tanks in 48 hours for each level of propagating. The results have also indicated that aerobic biological treatment of wastewater in ethanol plants containing high concentration of organic substances (COD 2840 - 4123 mg/l) with the rate added activated sludge of 30% results in a high efficiency in the elimination of organic matters, reaching 84.46%, while the case of without adding activated sludge, the treatment efficiency is only 63.72%